The present invention relates generally to a dynamic behavior control apparatus for an automotive vehicle, and more specifically, to a method and apparatus for determining whether a wheel of an automotive vehicle has lifted from the pavement.
Dynamic control systems for automotive vehicles have recently begun to be offered on various products. Dynamic control systems typically control the yaw of the vehicle by controlling the braking effort at various wheels of the vehicle. By regulating the amount of braking at each corner of the vehicle, the desired direction of the vehicle may be maintained.
Typically, the dynamic control systems do not address roll of the vehicle. For high profile vehicles in particular, it would be desirable to control the rollover characteristics of the vehicle to maintain the vehicle position with respect to the road. That is, it is desirable to maintain contact of each of the four tires of the vehicle on the road.
Vehicle rollover and tilt control (or body roll) are distinguishable dynamic characteristics. Tilt control maintains the body on a plane or nearly on a plane parallel to the road surface. Rollover control is used to maintain the vehicle wheels on the road surface.
Various methods have been proposed to determine whether roll is occurring. Typically, such systems include additional sensors from those of a dynamic stability control system. Therefore these systems are more expensive.
It would therefore be desirable to provide a rollover detection system having reduced costs and increased reliability in determining the presence of a rollover.
It is therefore one object of the invention to provide a rollover detection system that may be used in conjunction with the dynamic stability control system of the vehicle to determine rollover.
It is a further object of the invention to provide a rollover stability control system that provides steering correction in response to the detection of a potential rollover or wheel lift. The present invention provides a system for an automotive vehicle that includes a roll control system and a wheel lift detector is provided for an automotive vehicle. The automotive vehicle has wheels that when lifted from the road plane have less steering effort associated therewith. Preferably, each of the steered wheels has a steering actuator and an actuator sensor for monitoring the steering effort. The actuator sensor may be an implied sensor that monitors the drive current or pressure to monitor the load on the steering actuator. The load of the steering actuator is monitored and the actuator having the lightest load is determined. A steering perturbation is applied to the steering actuator and the steering effort is monitored during the perturbation. If the steering effort during the perturbation is lower than a lift threshold, then lift will be indicated. If the steering effort is greater than a lift threshold, then contact has been maintained with the road surface. In response to the indication of lift, corrective measures may be taken such as applying a counter steering effort or applying brakes in a predetermined fashion so as to counter the roll effect.
One advantage of the invention is that in vehicles employing a dynamic stability control system, additional sensors may not be required.
Other objects and features of the present invention will become apparent when viewed in light of the detailed description of the preferred embodiment when taken in conjunction with the attached drawings and appended claims.